Army ants of the genus Eciton are among the most well-studied of the social insects. Their sophisticated social organization, nomadic lifestyle, and role as top predators in tropical ecosystems have interested researchers for decades, revealing much about their biology, behavior and ecological significance. This work has had significant impact across disciplines, generating fundamental insights for the study of self-organization and providing inspiration for emerging fields like collective robotics. However, an important aspect of army ant behavior has been relatively understudied: the structures that Eciton ants build out of their own bodies. Understanding the mechanisms by which these structures form, their dynamic properties and their adaptive function at the colony level is the focus of this dissertation.
In the chapters that follow, I present the results of a series of field experiments conducted in Panama over the last few years, along with a set of models aimed at elucidating the mechanisms underlying the formation of self-assembled structures. I show that self-assemblages are a fundamental aspect of the behavior of the two most conspicuous and well-studied species of army ant, Eciton burchellii and Eciton hamatum, and provide significant adaptive benefits at the colony level. The deployment of self-assemblages by these two species is a key innovation that has contributed to their dominant ecological position as top predators in the tropical forests of the New World.